We are determining the development pattern of the multiple forms of cytochrome P-450. For each form, the substrate specificity and inducibility will be tested. We also plan to assess whether induction of a particular cytochrome alters the metabolism of mutagens detected with the Salmonella tester system of Ames. BIBLIOGRAPHIC REFERENCE: Resolution of two-forms of cytochrome P-450 from liver microsomes of rabbits treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin. Eric F. Johnson and U. Muller-Eberhard (1977) J. Biol. Chem. 252, in press.